The present invention relates to a chromatic confocal sensor and a measurement method that uses it.
From the past, the chromatic confocal technique has been used for measuring a height of an object to be measured and the like. For example, Japanese Patent Application Laid-open No. 2011-39026 (hereinafter, referred to as Patent Document 1) discloses a chromatic confocal displacement meter (hereinafter, referred to as chromatic sensor) as shown in FIG. 1. In the chromatic sensor, a color to be focused on a work changes on a one-on-one basis according to a height (displacement) of the work. By extracting light of a color to be focused on the work and specifying the color (optical wavelength), the height of the work that is in a one-on-one relationship with the color is measured (paragraphs [0002], [0003], etc. in specification of Patent Document 1).
A chromatic point sensor system disclosed in Japanese Patent Application Laid-open No. 2013-130581 (hereinafter, referred to as Patent Document 2) includes a light source and first and second optical paths connected thereto as shown in FIG. 1. By using the first optical path that is an optical path of a confocal system, a first output spectral profile including distance-dependent and distance-independent components is obtained. By using the second optical path, a second output spectral profile including a distance-independent component (without distance-dependent component) is obtained. By correcting the first output spectral profile on the basis of the second output spectral profile, it becomes possible to correct a measurement error arising from a change in measurement condition, in particular, a measurement error arising from spectral reflectance characteristics specific to a work (paragraphs [0009], [0013], [0029]-[0032], etc. of Patent Document 2).